1. Field of the Invention
The present invention relates to method and apparatus for stabilizing material physical properties of recyclable bumpers which promote the reuse of used bumpers of disused vehicles or failed bumpers for vehicles
2. Description of the Related Art
Conventionally, recyclable bumpers are cleaned, fractured and dried for conversion into fractured raw material, and coating on the fractured material is then separated therefrom to produce a recycled matrix for reuse. However, the recycled matrix has not been used for producing automotive bumpers as it is but has been used at the most only for production of bumper cores and is generally used for producing other automotive parts. Even when used to produce other automotive parts, the recycled matrix is used indiscriminately for parts which are not visible and in particular for those which are easy to be molded.
The difference in material physical properties between the recycled matrix produced from the recyclable bumpers and a virgin material is conspicuous when compared, and this difference in material physical properties causes scattering in material physical properties of a recycled product, leading to a problem that recycled products are liable to molding failures. Consequently, using the recycled material for painted parts as it is results in the fact that the external product quality cannot reach an acceptable level. Even when the material is reused for parts that are invisible, there is caused a problem that molds need to be modified due to the different material physical properties. In addition, in a molding method in which the recycled material is adopted for a material for bumper cores, there is a problem that the productivity is deteriorated due to differences in configuration and thickness of bumpers. In particular, with the recycled material from which coating is separated, there is a problem that the material cannot be adopted due to scattering in material physical properties for large resin molded products such as vehicle bumpers which are high in difficulty in molding.
The present invention was made in view of the problems and an object thereof is to provide novel method and apparatus for stabilizing material physical properties of recyclable bumpers which allow a recycled material from recyclable bumpers to be used for large resin parts such as painted bumpers which require strict external product quality and which can provide as good a quality as a virgin material from a 100% recycled material,
With a view to attaining the object, according an aspect of the invention, there is provided a method for stabilizing material physical properties of recyclable bumpers comprising the steps of separating coating from the fractured material obtained by cleaning, fracturing and drying recyclable bumpers, to thereby make a recycled matrix, mixing an additive with the recycled matrix, melting and extruding the mixed matrix with an extrusion machine and cutting the molten and extruded matrix to produce pellets melting, and introducing the pellets into a tank of a predetermined capacity and mixing the pellets in the tank for a predetermined period of time while delivering the pellets in the tank to an introduction opening of the tank again for reintroduction into the tank in parallel with the pellets that are newly introduced. Namely, with the method according to the invention, since the pellets in the tank are mixed for a predetermined period of time while introducing the pellets that are newly introduced, scattering in material physical properties is restrained, and moreover, residual coating pieces that affect the material physical properties are dispersed to stabilize the material physical properties.